Asthma admission among children in Hong Kong during the first year of the COVID-19 pandemic

Background Multiple nonpharmaceutical interventions (NPIs) had been introduced in Hong Kong during coronavirus disease 2019 (COVID-19) pandemic. The impact on asthma admission, which was closely related to viral infection, was of concern. Objective The study aimed to identify the impact of NPIs on pediatric asthma admissions and their association with respiratory viruses. Methods We conducted a retrospective observational study to compare the difference in pediatric asthma hospital admission rates between pre-COVID-19 and COVID-19 periods. Information on demographics, nasopharyngeal specimen results, ventilatory support, intensive care admission, hospital stay duration, asthma control therapy, and previous admission episodes was collected. Weather parameters including temperature, rainfall, humidity, and air quality data that was reflected by the air quality health index were recorded. Results A total of 1808 pediatric asthma admissions were recorded during the pre-COVID-19 period while there were 62 admissions during COVID-19 period, among which 54 admissions from the pre-COVID-19 period and 4 admissions from COVID-19 period were excluded. Weekly pediatric asthma admissions per total pediatric admissions during COVID-19 was one-third of that during the pre-COVID-19 period (0.3% vs. 0.9%, p < 0.001). During COVID-19 period, a significantly lower percentage of respiratory virus isolates was noted (58.6% vs. 72.6%, p = 0.019). Poisson regression analysis showed that the COVID-19 period (odds ratio [OR] = 0.202, 95% confidence interval [CI, 0.16-0.26]; p <= 0.001), summer vacation period (OR = 0.512, 95% CI [0.43-0.62]; p <= 0.001), and humidity (OR = 0.99, 95% CI [0.98-1.00]; p = 0.004) were independent protective factors for asthma admission. Conclusions There was a significant reduction in pediatric asthma hospitalizations and respiratory virus isolates in the first year of COVID-19 pandemic in Hong Kong with the implementation of NPIs. Rhinovirus remained the key respiratory virus isolate. Incorporation of appropriate NPIs in long run could reduce virus infection-related pediatric asthma admission.